Soldering was widely used for mounting onto a circuit substrate of a semiconductor device. However, semiconductor devices have been packaged and modularized lately, so that methods of connecting contact electrodes of a chip package or module to terminal electrodes of a circuit substrate were devised.
Among the methods, a method of carrying out operation tests by mounting a package or a module having ball-type solder as contact electrodes on a socket applied to check a semiconductor device called the BGA (Ball Grid Array) socket was found effective since the socket has high contact reliablity and endurance. (As an example, the socket is "TEXTOOL" BGA Socket (IC Socket for test and burn-in) manufactured by Sumitomo 3M Limited.)
An embodiment of the above-noted conventional method of checking a semiconductor device is explained by referring to the figures.
FIG. 7 is a perspective view of a conventional socket for checking a semiconductor device. FIG. 8 is an exploded perspective view of the conventional socket shown in FIG. 7. In FIG. 7 and FIG. 8, 101 is a lid, 102 is a latch, 103 is a nest, 104 is a contact pin, 105 is a base, and 106 is the BGA socket.
FIG. 9 is a cross-sectional view of the socket as used with a semiconductor device. FIG. 10 is an enlarged cross-sectional view of part of FIG. 9. In FIG. 9 and FIG. 10, 107 is an LSI chip, 108 is a two-stage protruded electrode, 109 is a bonding layer made of conductive adhesive, 110 is a terminal electrode of a chip carrier, 111 is a chip carrier, 112 is a ball-type protruded electrode, 113 is a spacer, and 114 is a semiconductor device.
The conventional method of checking a semiconductor device is explained by referring to FIGS. 7, 8, 9 and 10.
The BGA socket is prepared as shown in FIG. 7 and FIG. 8. As shown in FIG. 9 and FIG. 10, the position of ball-type protruded electrodes 112 of package or module 114 is adjusted to contact pins 104 of BGA socket 106, facing the contact pins. Then, the protruded electrodes are placed on the contact pins. Spacers 113 are deposited on chip carrier 111 and are pressed from the top by lid 101, with lid 101 being fixed by latch 102. As a result, ball-type protruded electrodes 112 of package or module 114 are set in contact with contact pins 104, so that electric continuity is established and the semiconductor device is checked electrically.
However, the following problems are found in the above-mentioned method:
1. the chip carrier where an LSI chip is mounted is pressed with a large load of several kg, so that the substrate is bent and the connection of the LSI chip becomes unstable; PA1 2. the ball-type protruded electrodes are applied as contact electrodes, so that the protruded electrodes cannot sufficiently contact the contact pins of the BGA socket when the electrodes are not perfectly identical to each other; and PA1 3. the contact pin of the BGA socket is in a spring form, so that the height of the pin is required to be more than 100 .mu.m to increase contact between the pin and the protruded electrode.